1. Field of the Invention
The present invention relates to a holder device for analyzing characteristics of a dosimeter.
2. Description of the Related Art
In order to destroy cancer cells or to alleviate pains of cancer patients, therapeutic radiation used for medical purposes is aimed to a tumor of a cancer patient so as to prevent further propagation of a cancer cell.
Such a radiation treatment is used to avoid relapse of cancer when there is a high possibility that cancer cells are not entirely eliminated even after surgery. In addition, the radiation treatment is used when surgery is not available, or when surgery is less effective than the radiation treatment, or when patient can benefit by both surgery and radiation treatment. Furthermore, the radiation treatment is used to maximize anticancer effect after the patient receives an anticancer drug treatment.
The radiation treatment is carried out using an expensive medical device called a “linear accelerator”. The linear accelerator can emit an X-ray and an electron ray and can regulate an output energy level. Further, the linear accelerator can provide a high dose rate. Therefore, at present, the linear accelerator is used as a standard device for radiation treatment.
What is the most important factor in the use of the linear accelerator during the radiation treatment is that the linear accelerator has to emit radiation with an optimal energy level. This is because a best therapeutic effect can be expected when the radiation is irradiated with optimal energy corresponding to the state, the size, or the depth of tumor.
Therefore, prior to using the linear accelerator, a precision examination has to be performed to check whether the linear accelerator normally operates, in particular, whether a radiation dose is properly regulated to emit radiation with suitable energy. For this, a variety of devices for measuring the radiation dose is used.
One example of the devices for measuring the radiation dose is a dosimeter which measures an absorbed radiation dose or an exposure radiation dose to know how much the radiation has been irradiated. The dosimeter may be an ionization chamber or a thermoluminescent dosimeter (TLD). Recently, a metal oxide semiconductor field effect transistor (MOSFET) dosimeter is also used to measure even a surface dose of a region of interest.
The MOSFET dosimeter is a semiconductor device, in which a radiation dose can be checked in the real time basis with an easy operation. In addition, since a plurality of MOSFET dosimeters can be attached to be used at the same time, a dose distribution can be measured at a portion where a (2-dimensional) dose distribution rapidly changes. Due to its compact and thin size, the MOSFET dosimeter can be attached on the skin surface. Thus, the dose distribution can be measured at a portion having a large curvature, such as the flank, the shoulder, the breast, and so one.
For the clinical use, preferably, characteristics of the MOSFET dosimeter are analyzed in advance. This is because, even if MOSFET dosimeters are manufactured according to the same standard through an assembly line, sensing capability is slightly different from one MOSFET dosimeter to another, and in particular, (due to its flat plane structure) an absorbed radiation dose may differ according to a radiation angle when radiation is irradiated to the MOSFET dosimeters.
As such, only when the characteristics of the MOSFET dosimeter to be used are analyzed in advance, accuracy control of a radiation treatment device can be properly performed, and a radiation dose can be accurately measured for other radiation treatments as well.
However, since the characteristic analysis on the MOSFET dosimeter has not seriously been taken into account in the past, there is no device designed for characteristic analysis.